| 摘要 |
PROBLEM TO BE SOLVED: To provide a starting circuit capable of preventing a constant voltage circuit from being influenced by the variation of temperature and that of power supply voltage. SOLUTION: The starting circuit 2 is provided with a switching element Q1 for supplying power to be turned on at the time of starting to generate reference voltage to a contant voltage circuit 1 and a control circuit 3 for controlling the ON/OFF of the element Q1. The circuit 3 is provided with a comparator 3a for comparing the output voltage Vo of the circuit 1 with a threshold Vr. When the circuit 1 is started its output voltage Vo is boosted, and when the output voltage Vo exceeds the threshold voltage Vr of the comparator 3a, the output of the comparator 3a is changed from an H level to an L level, the element Q1 is turned off, and power supply from a control power source E through the element Q1 is stopped. Consequently the circuit 1 can be prevented from being influenced by the temperature variation of the starting circuit 2 and the variation of power supply voltage.
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